Many reel-to-reel manufacturing processes include one or more printing process stages, and for several successive printing process stages ready-made register control systems, are available which are based on the identification of marks printed in each printing unit by means of computer vision and on controlling the printing units on the basis of the observations made by the computer vision on the marks. A good register control system is capable of aligning printing process stages carried out in different units in such a way that, for example, a high-quality colour picture is produced in the finished product even though each colour is printed in its own unit.
Laser has already found its way into many industrial processes and it will become more widely used also in different reel-to-reel manufacturing processes. At the laser processing stage, procedures are often carried out on the material travelling from reel to reel, which do not leave any marks on the base or carrier material of the moving web, but bring about changes in some other part or layer of the web—from the point of view of the process, it is specifically advantageous if the wavelength and other properties of the laser can be selected in such a way that the laser has no effect on the base or carrier material of the web. A problem arising in this case is that, unlike the printing process stages, the laser process stage cannot produce any such marks or traces in the base or carrier material of the web, which could be utilised in register control. This type of laser light is typically also not shone on the surface of the base material.
It is often specifically the reel-to-reel manufacturing processes including a laser process stage that are the ones with a particularly great need for mutual alignment, or register control, of process stages, and thus the inability of the laser to produce a suitable mark for register control is a real problem.
The aim of the invention is to offer a solution by means of which a reel-to-reel manufacturing process including printing process stages and/or laser process stages can be provided with register control for ensuring the mutual alignment of the process stages. The invention also provides a solution for the mutual alignment of scanners in a laser apparatus comprising several parallel laser patterning devices.